PITTSBURGH — A.J. Burnett doesn’t lead the major leagues in strikeouts. He just wants to and is awful close.

“I’m trying to keep up with Yu Darvish, but he’s pretty filthy,” the Pittsburgh Pirates’ ace said of the Texas Rangers’ right-hander.

Burnett allowed one run and struck out nine in seven shutout innings, and call-up Jordy Mercer hit a tiebreaking home run to lead the Pirates to a 3-1 victory over the Washington Nationals on Friday night.

Burnett (3-2) gave up five hits and one walk in winning his third straight game after going 0-2 in his first three starts. He also raised his NL-leading strikeout total to 57. Darvish tops the majors with 58.

“Strikeouts are always good to have and I like to put people away,” Burnett said. “There will be some nights where I won’t have many strikeouts, so you take them when you can get them.”

Burnett has allowed just five earned runs in 25 innings in his last four starts for an ERA of 1.80.

Pirates manager Clint Hurdle believes Burnett is pitching as well as at any time during his two seasons in Pittsburgh. Burnett won 16 games last year.

“He’s approaching every single pitch he makes with total conviction,” Hurdle said.

Mercer’s two-run home run off Ross Detwiler (1-3) in the fifth inning put the Pirates ahead 3-1. Mercer was recalled from Triple-A Indianapolis before the game when second baseman Neil Walker was placed on the disabled list with a right hand injury.

Mercer made his major league debut last season with Pittsburgh and appeared in 42 games, hitting one home run in 68 at-bats.

“I am just as excited to be here as last year, but I don’t have the nerves this time,” Mercer said. “I felt a lot more comfortable. I didn’t know if I was even going to be in the lineup until I got here. We were playing in Allentown (Pa.) against Lehigh Valley and they told me to get on a plane to Pittsburgh. It was nice to get a chance to play and even nicer to contribute to a win.”

Detwiler went five innings and gave up three runs and six hits while walking two and striking out five.

The Pirates won for the fourth time in six games and the Nationals lost for the fourth time in six games.

Andrew McCutchen had three hits, including a home run, for Pittsburgh. Leadoff man Starling Marte and Gaby Sanchez added two hits apiece.

Mark Melancon pitched a scoreless eighth and Jason Grilli shut out the Nationals in the ninth for his 12th save in as many chances.

Washington first baseman Adam LaRoche went 2-for-3 to equal the number of hits he had in his previous 11 games and 38 at-bats.

McCutchen hit a solo shot off Detwiler in the first inning for a 1-0 lead. The center fielder has 10 home runs against Washington in 24 games.

“It’s kind of weird, but it was the same exact pitch on both home runs and it’s what ended up beating me,” Detwiler said. “I tried to get a fastball to the outside corner and they both cut back over the plate and their guys hit them, which is what they’re supposed to do and what they get paid for.”

The Nationals tied it in the fourth on Danny Espinosa’s RBI single. It was just the second hit in the last 23 at-bats for the second baseman.

Nationals hitters struck out 14 times as Melancon had two and Grilli had three.

“We’ve got good hitters but we’re striking out more than we should,” Nationals manager Davey Johnson said. “I don’t know if it’s being aggressive early in the count or not, but I do feel we’re trying too hard to make things happen. Everyone just needs to relax a little bit.”

NOTES: The Pirates are hoping Walker can return May 12. ... Pittsburgh selected the contract of veteran RHP Jose Contreras from Triple-A Indianapolis and optioned RHP Jared Hughes to Triple-A. ... Washington RF Jayson Werth did not play and is likely to miss the three-game series with a strained right hamstring. ... Pittsburgh RHP Charlie Morton was removed after three innings Friday night from his rehab start with Triple-A Indianapolis because of shoulder inflammation. He is recovering from Tommy John elbow surgery performed last June. ... Nationals RHP Stephen Strasburg (1-4, 3.16) looks to snap his four-game losing streak today when he faces left-hander Jeff Locke (3-1, 2.83), who has pitched 13 scoreless innings while winning his last two starts.